Endodontic treatment involves thorough cleaning and shaping of root canal to debride all narcotic tissues and microorganism and complete fluid tight obturation (filling) of the entire root canal system.
Root canal morphology in different teeth is vastly different. Even in the same teeth in the population, the morphology of canal system is diverse. Most of the canals are curved. There is presence of extra canals, lateral and accessory canals, cul-de-sac etc. Filling the total root canal space to provide fluid-tight seal is a challenge. There are also several controversies regarding the ideal level of termination of root canal filling—whether to keep it flush with radiographic apex or to keep it 1 mm, short of the apex. The level of filling recommended is different in different clinical cases; whether the pulp was vital or non-vial at the start of the treatment, whether there was periapical pathology, diagnosed clinically or radiographically, whether alveolar bone and/or root resorption was present etc. Also, if apical constriction is not present as in cases of wide open apex and apical root resorption, achieving a perfect seal at the apex becomes almost impossible and involves additional steps of placing a biocompatible barrier material first and then obturating the canals. Then there are controversies whether over-extended (extruded) sealer cement is desirable or causes adverse reaction.
To meet all these challenges, a plethora of root canal obturating materials as well as instrument systems has been developed over the years. Each of these systems is technique sensitive and demands precision and adequate training to be able to use it efficiently, besides being expensive. The obturating material has to adapt as close to canal walls as possible, preferably bond with the walls and hence adequate pre-conditioning of canal walls as well as sealer cement is required. Use of all these material also involves safety and biocompatibility with the tissues. Hence, a non-obturation method of endodontic treatment of non-vital, infected teeth is highly desirable.
The technique of “non-obturation, regenerative endodontic treatment” will greatly simplify the endodontic treatment. The technique is based on regenerative potential of stem cells, locally available in the peri-radicular region of teeth, which are stimulated to induce healing and deposition of a natural barrier (seal) at the root apex, eliminating the need for cumbersome obturation process.
Endodontic literature states that approx. 60% of endodontic failures are due to inadequate obturation of root canal system. Therefore, if the step of obturation is eliminated altogether, the endodontic treatment is simplified to a large extent. The technique is simple, highly cost effective and has the potential to achieve periapical healing.
The technique involves recruiting stem cells and growth factors from the periapical region to affect healing and regeneration. If proved effective, this study can trigger further research in regenerative therapies in Endodontics in particular and in Dentistry in general.
This procedure is a novel procedure which was conceived by going through extensive literature search and our own previous clinical study on “Revascularization for inducing apexogenesis/apexification in non-vital, immature permanent incisors: a pilot study” which is published in Journal of Endodontics, a highly acclaimed International Journal on Endodontics. (Shah N, Logani A, Bhasker U and Aggarwal V. Revascularization for inducing apexogenesis/apexification in non-vital, immature permanent incisors: a pilot study. J. Endod. 2007; 34: 919-925.
In this study, stem cells i.e., BMMSC, PDLSC, DPSC were stimulated by over-instrumentation into the periapical tissues through the root canal in immature, non-vital infected teeth. Over-instrumentation induced bleeding into the canal which was allowed to form a clot, into which the new capillaries and stem cells could proliferate. Various growth factors like PDGF, VEGF etc. from blood, bone marrow and dentin affect differentiation of these stem cells into fibroblasts, cementoblasts, osteoblasts etc. which lay down collagen fibrils and hard tissues in the form of cementum, bone, osteodentin etc. The results of this study indicated that recruitment of locally available stem cells not only deposited the hard tissue at the apical end (affecting apical seal) but also on thin lateral dentinal walls and even elongation of root i.e. complete maturation of poorly developed root. Based on the very encouraging results in immature teeth, where periapical healing and tissue regeneration was achieved in immature teeth without root canal obturation, it was conceived to test the process in fully developed mature teeth, adhering to the principles of elimination of root canal infection by thorough cleaning and shaping of root canals and proper sealing of the coronal cavity.
Occasional cases in dental literature have shown that periapical infection will heal following thorough debridement and infection control in the root canal system even without obturation of root canals. An experimental animal study reported in 2006 from UCLA tested the outcome of endodontic treatment with and without obturation of root canal system and found no significant difference in healing, proven by histology of peri-radicular tissues.
The existing modern endodontic treatment requires that root canal system be completely disinfected and obturated in three dimensions to achieve a fluid tight seal of the root canal system. In recent past, importance of coronal seal is realized to be as important as apical seal to prevent micro-leakage, bacterial ingress and re-infection of the canal system and periapical tissues.
To achieve these objectives, a very systematic, exacting and highly technical procedures are established. Not only the root canal system need to be chemo-mechanically prepared to disinfect the canal system, it also needs to be shaped to receive and compact the obturating material in three dimension to a specific apical limit, dictated by several factors like presence or absence of periapical lesion, root resorption etc. The most preferred obturating material till date is gutta percha rolled into different sizes of cones/points and is being used with sealer cement. There are several techniques of obturation such as lateral and vertical condensation, thermoplasticised Gutta percha obturation, thermo-mechanical compaction, injectable gutta percha filling etc. Each of these obturation systems require that canal be shaped according to the type of obturating technique to be followed. In addition, there are several sealer cements being used, each with its own advantages and limitations and biocompatibility behavior. More recently, resin based obturating materials and sealers are promoted to achieve bonding with the root canal walls. After root canal obturation, coronal seal is given in the form of a restoration or crown to prevent future re-infection.
The case requires regular follow up at an interval of 6 months till at least 2 yrs to categorize the healing as good, satisfactory or poor, both by clinical and radiographic method.
Root canal obturation is an exacting technique, demanding rigorous training and clinical skills. Each of the obturation technique and system (obturation equipments) require canals to be prepared accordingly. A large inventory of obturation systems and materials is required to obturate different canal systems. All these factors put increased demand on operators' skill and time and finally increase the cost of treatment. Also, as it increases the treatment time, only a few teeth from amongst those requiring endodontic treatment can be treated, the rest being condemned to extraction. (Loss of tooth).
All the above drawbacks are overcome by the new treatment approach proposed, i.e. achieving a biological seal rather than mechanical seal obtained by artificial obturating materials, the “Non-obturation endodontic treatment”. It not only dispenses with root canal obturation step with all its drawbacks, it simplifies the endodontic treatment, reduces the treatment time and ultimately reduces the cost of treatment. This new technique would provide the clinician an opportunity to save more number of pulp and periapically involved teeth, which otherwise would have been lost to extraction.
Another significant advantage of this novel treatment approach is its significant contribution towards understanding the role of stem cells and signaling molecules in healing mechanism of periapical pathologies, regeneration of damaged tissues and achieving biological seal (SealBio) at the root apex, by recruiting indigenous, locally available stem cells and growth factors. This technique can trigger further research in tissue engineering for repair and regeneration in other oral pathologies in future.